A Study of Elacestrant Versus Standard Endocrine Therapy in Women and Men With ER+,HER2-, Early Breast Cancer With High Risk of Recurrence

Required: ESR1 expression (≥10% by IHC)

ER+ (≥10% by immunohistochemistry [IHC])

Required: HER2 (ERBB2) wild-type (IHC 0, 1+, or 2+ with ISH-negative (not amplified))

HER2- (tumors with an IHC score of 0, 1+, or 2+ with in situ hybridization [ISH]-negative [not amplified])

Must have received: endocrine therapy (aromatase inhibitor, tamoxifen) — adjuvant

currently taking endocrine therapy (aromatase inhibitors or tamoxifen) and have received at least 24 months but not more than 60 months of endocrine therapy at the time of randomization (Cycle 1 Day 1 [C1D1])

Cannot have received: CDK4/6 inhibitor

Exception: must have already completed or discontinued these treatments

Participants who received prior CDK4/6i or a poly adenosine diphosphate-ribose polymerase inhibitor must have already completed or discontinued these treatments

Cannot have received: PARP inhibitor

Exception: must have already completed or discontinued these treatments

Participants who received prior CDK4/6i or a poly adenosine diphosphate-ribose polymerase inhibitor must have already completed or discontinued these treatments

Cannot have received: adjuvant endocrine therapy

Exception: more than a 6-month continuous interruption of prior SoC adjuvant endocrine therapy or off current adjuvant endocrine therapy more than 6 months prior to randomization

Participants who have had more than a 6-month continuous interruption of prior SoC adjuvant endocrine therapy or who are off current adjuvant endocrine therapy more than 6 months prior to randomization